Is it my phone or my alarm app?

Quick test: set an alarm in Apple's own Clock app for a minute from now, with the phone on silent. If that rings, your phone is fine and the app is the problem, which means it is almost certainly built on notifications instead of a real alarm.

Why does my alarm work some days but not others?

That pattern points at repeat settings rather than volume. Check which weekdays the alarm repeats on, and whether a sleep schedule in the Health app is setting a different wake time than the alarm you are looking at.

Does NanoTimer fix Apple's alarm?

No, and we do not promise that. If the Clock app is not working, it is in your settings; the list above solves it. NanoTimer is for people who want an alarm app that goes off just as reliably.

Why doesn't my alarm go off?

Almost always it is the ringer volume, a Focus or a setting, not a broken phone. Here is what actually happens, and why third-party alarm apps fail more often than your phone's own alarm.

Apple's alarm does ring on silent

Worth knowing first: the Alarm in Apple's Clock app rings even when your phone is on silent. Apple gives its own alarm that exception. So if it still does not go off, it is almost never the silent switch, but one of the things below.

Work through this list

In the order of how often it is the cause:

The ringer volume is too low. The volume buttons control media volume as soon as sound is playing; the alarm uses the ringer volume. Set that separately under Settings, Sounds & Haptics.
The alarm is switched off. The toggle in the Clock app has to be green.
AM and PM mixed up. On a 12-hour clock 7:00 in the morning is not 19:00.
A sleep schedule or Focus took over. A Sleep alarm is separate from your regular alarms.
The alarm sound is set to none. Then it only vibrates.
Your phone was off or the battery was dead. Then no alarm rings.

Why third-party alarm apps fail more often

This is the real reason people stop trusting their alarm app. For a long time a third-party app could not set a real alarm. Those apps lean on notifications, and notifications are muted by the silent switch, by a Focus and by your notification volume. Exactly where Apple's alarm gets an exception, a regular app does not.

Some apps work around it by playing silent audio in the background so the system keeps them alive. That drains battery and is fragile: if iOS closes the app, your alarm is gone.

What AlarmKit changes

Since iOS 26 there is AlarmKit. With it an app can set a real alarm, treated like the system alarm: it breaks through the silent switch and through a Focus, and keeps ringing until you stop it.

NanoTimer uses AlarmKit. That is the difference between a notification hoping you hear it, and an alarm that goes off.

An alarm that does go off

NanoTimer uses AlarmKit: it breaks through silent and Focus and keeps ringing until you stop it. Free, no ads, no subscription.

Open on your phoneOpens the right tab in NanoTimer on your iPhone.

Download on theApp StoreLink coming soon

Frequently asked questions

Is it my phone or my alarm app?: Quick test: set an alarm in Apple's own Clock app for a minute from now, with the phone on silent. If that rings, your phone is fine and the app is the problem, which means it is almost certainly built on notifications instead of a real alarm.
Why does my alarm work some days but not others?: That pattern points at repeat settings rather than volume. Check which weekdays the alarm repeats on, and whether a sleep schedule in the Health app is setting a different wake time than the alarm you are looking at.
Does NanoTimer fix Apple's alarm?: No, and we do not promise that. If the Clock app is not working, it is in your settings; the list above solves it. NanoTimer is for people who want an alarm app that goes off just as reliably.